The present invention relates to a magnetic head slider and a magnetic head slider inspection device. More particularly, the present invention relates to a magnetic head slider which is held above a revolving disk medium, and has a built-in element for changing the resistance value in accordance with external magnetic fields.
Generally, the magnetic disk device includes a magnetic head slider which is levitated in proximity above the revolving magnetic disk. The magnetic head slider has a built-in reproducing head for reading magnetic information recorded in the magnetic disk medium.
The reproducing head is formed of a magnetic body, and configured to change the resistance value in accordance with direction and magnitude of incident magnetic field externally input to the reproducing head. Meanwhile, the magnetic disk medium emits the magnetic field from the magnetic layer therein toward its surface. The direction of the magnetic field corresponds to the information recorded in the magnetic disk medium. Magnitude of the magnetic field corresponds to density of the information recorded in the magnetic disk medium. The reproducing head is brought into the magnetic field emitted from the magnetic disk medium so that the resistance value of the reproducing head changes in accordance with the information recorded in the magnetic disk medium. The magnetic disk device is structured to read the recorded information by measuring variation of the resistance value of the reproducing head using an electric circuit.
For developing the reproducing head, the head is required to be designed to increase variation of the measured resistance value of the reproducing head to the external magnetic field. Hereinafter, the variation of the resistance value of the reproducing head to the external magnetic field will be referred to as “performance of the reproducing head”.
There is often the case that when the magnetic disk device is externally damaged, the magnetic head slider is brought into contact with the magnetic disk medium to damage the reproducing head, thus changing performance of the reproducing head. Hereinafter, performance change in the reproducing head caused by the damage will be referred to as “damage amount of the reproducing head”. For this, it is important to design the reproducing head with a small amount of damage, that is, high durability against the damage of the reproducing head measured when the magnetic head slider is brought into contact with the magnetic disk medium.
In the method for measuring performance and damage amount of the reproducing head, the magnetic head slider is levitated by the magnetic disk device so as to capture the magnetic field from the magnetic disk medium with the reproducing head for measuring the variation of the resistance value of the reproducing head. In another method, the magnetic head slider as the single body is used to measure variation in the resistance value of the reproducing head to the external magnetic field while externally applying the magnetic field to the magnetic head slider. As an example, the method according to Japanese Unexamined Patent Publication No. 5-307718 or the method using the device introduced in the Non-patent Document of QST-2002.pdf (web page: http://www.us-isi.com/QST-2002.htm) may be employed.
With the aforementioned method using the magnetic disk device, magnitude of the magnetic field applied to the reproducing head varies in accordance with the structure of the magnetic disk medium, levitation distance of the magnetic head slider, and the recording density of the magnetic disk medium. It is therefore difficult to quantitatively measure performance of the reproducing head.
With the aforementioned method using the magnetic head slider as a single unit, the state of the levitated magnetic head slider during the measurement cannot be reproduced. Generally, the magnetic head slider within the magnetic disk device is levitated above the magnetic disk medium which revolves at 4000 rpm to 15000 rpm while keeping the gap of several nano meters. While it is levitated, the temperature of the reproducing head changes owing to heat transfer. It is therefore difficult to derive performance of the levitated reproducing head from the performance of the reproducing head which is not levitated. Furthermore, it is also difficult to obtain the damage amount of the reproducing head when the magnetic head slider is brought into contact with the magnetic disk medium.